There is currently a large and growing population of patients (mostly diabetic patients) that are likely to suffer a foot and/or ankle ulcer at some point. It is estimated that there are about 26 million diabetics in the United States alone and that about 4 to about 5.2 million suffer from foot ulcers. It is estimated that about 15% to 20% of diabetic patients fall into this group. The costs of diabetic treatments are currently estimated at about $132,000,000 of which about ⅓ is related to treating foot ulcers.
Chronic ulceration of the foot is one of the most common and difficult to treat consequences of diabetes and other neuropathogenic conditions. Diabetic foot ulcerations are noted to occur in 15-25% of diabetic patients in the course of their lifetime. Diabetic foot ulcerations are subject to unopposed repetitive microtrauma, compounded by diabetic systemic comorbidities such as peripheral neuropathy, structural changes, and ischemia. Neuropathic feet are also at risk for a Charcot deformity, which can completely change normal pedal osseous architecture, creating increased foci of plantar pressures at risk for ulceration.
Neuropathic pedal ulcerations from diabetes and other etiologies are common and costly. The statistical morbidity of diabetic foot ulcers is sobering and often overlooked. The diabetic population now numbers over 26 million people in the United States. The global “diabetic foot disease” is “a potentially devastating complication of a disease that is reaching epidemic proportions . . . someone, somewhere, looses a leg because of diabetes every 30 seconds of every day.” Andrew Boulton, et al., The global burden of diabetic foot disease, 366. 9498 LANCET 1719 (2005). Diabetics, compared to non-diabetics, are 30 times more likely to suffer a lower extremity amputation over the course of their lives and have a 10 fold greater risk of being hospitalized for bone and soft tissue infections. L A Lavery, et al., Risk factors for foot infections in individuals with diabetes, 29(6) Diabetes Care 1288 (2006). Diabetic foot ulcerations precede 85% of all non-traumatic lower extremity amputations. D G Armstrong et al., Guest editorial: are diabetes-related wounds and amputations worse than cancer?, 4(4) INT'L WOUND J. 286 (Dec. 2007). The five-year mortality after a lower extremity amputation has been shown to be 45%, greater than or equal to that of other deadly cancers (e.g., colon, lung, and pancreatic). Id.
Foot ulcers may result from a number of factors. Contributing factors may include sepsis, arteriopathy, and neuropathy. In some cases, the diabetic condition leads to the generation of avascular tissue at subcutaneous levels or in deep tissue. An avascular condition and patient immobility generally lead to pressure and break-down of the affected tissues. This chronic condition produces break-down of the overlying skin, which may in turn lead to secondary infection.
Recurrent ulcerations become common in neuropathic patients and increase risk of local and systemic infection, repetitive hospitalization, and potential amputation. These wounds can be challenging and have a high rate of recurrence despite successful episodes of wound care.
Current treatments are underwhelming and focus on treating broken skin and address superficial aspects of ulcers. The goal of ulcer treatment is generally to resolve the ulcer and reduce recurrence. To date, the focus of treatment has been on promoting the healing of the superficial aspects of the ulcer at the epidermal level and reducing the bacterial burden. The end result of conventional treatments may be reduction in ulcer size, complete resolution of the ulcer size, or a recurrence of the ulcer.
Moreover, current therapies designed to heal the ulceration are unpredictable, costly and time consuming, and even when successful may not address underlying etiologies of osseous, scar, or bursa origin and thereby often lead to recurrence in the same location. A recurrence rate of 40% over the four months following healing has been cited by concensus panels. The International Diabetes Foundation reports recurrence rates of over 50% after three years, and notes that “costs of diabetic foot disease therefore include not only the immediate episode, but social services, home care, and subsequent ulcers.”
Current treatments may be separated into two types: indirect and direct. Indirect treatments include off-loading of weight and/or pressure from the affected area through customized footwear or by using assistive devices, such as crutches, scooters, etc. Direct treatments include debridement of the ulcer surface, topical wound dressing to control the wound bed moisture, and adjunctive methods. Adjunctive methods include grafts/skin substitutes, negative pressure, hyperbaric oxygen, and phototherapy.
Conventional treatments share a number of features. The best outcomes include ulcer healing in 50-70% of cases but with a recurrence rate approaching 100% about three months after the treatment. Most methods are provider intensive in that repeat procedures are required. Patient compliance is also an issue the limits the success of any of these procedures. Ultimately, current procedures are costly.
In addition to the grave considerations of morbidity, neuropathic ulcerations pose a high financial burden. Up to ⅓ of the $116 billion in direct costs generated by the treatment of diabetes and its complications has been attributed to treatment of diabetic foot ulcers (Vickie Driver, et al., The costs of diabetic foot: the economic case for the limb salvage team, 52(3) J. VASCULAR SURGERY 17S (2010)) and annual direct costs of diabetic limb complications are more expensive than five of the most expensive cancers: breast, colorectal, lung, prostate, and leukemia (Neal R. Barshes, et al., The system of care for the diabetic foot: objectives, outcomes, and opportunities, 4 DIABETIC FOOT & ANKLE 21847 (2013)).
A retrospective nested case-control study found that relative cost of care for diabetics with ulcers was 2.4 times higher than diabetics without ulcers prior to ulceration, jumping to 5.4 times higher in the year after the ulcer, and returning to 2.8 times higher two years after the ulcer. Furthermore, the 1999 study showed the excess cost of a diabetic foot ulcer was $26,490 in ulcer patients during the year of the ulcer episode, persisting at $17,245 in the following year, compared to diabetics without ulceration with excess costs of $4927 and $5110 during the same respective time periods measured. S D Ramsey, et al., Incidence, outcomes, and cost of foot ulcers in patients with diabetes, 22(3) DIABETES CARE 382 (1999).
When wound healing is unsuccessful, the costs of amputation and dealing with post amputation care are considerable as well. A 2011 report showed approximately $52,000 is reimbursed annually for a Medicare beneficiary with diabetes and a lower extremity amputation. D. MARGOLIS, ET AL. ECONOMIC BURDEN OF DIABETIC FOOT ULCERS AND AMPUTATION: DIABETIC FOOT ULCERS, DATA POINTS #3 AGENCY FOR HEALTHCARE RESEARCH AND QUALITY, U.S. DEPT. OF HEALTH AND HUMAN SERVICES (Jan. 2011). In an analysis of a decade of inpatient admissions (2001-2010), Skrepnek found that of the 388.4 million inpatient admissions in the US, 66.1 million involved a diagnosis of diabetes (17%), 2.5 million involved diabetic foot ulcers (4%), and the 10-year total costs of the inpatient national bill was $2.4 trillion for diabetes and $113 billion for diabetic foot ulcers. G. Skrepnek, Foot-in-wallet disease: Tripped up by “cost-saving” reductions, Paper presented at DF Con 2014 (Mar. 20-22, 2014).
Accordingly, a need exists for the further development of systems and methods for effectively treatment wounds, not just foot/ankle ulcers.